The present invention relates to a method for drying a compressed gas and a compressor installation provided with a dryer.
Specifically, the invention relates to a dryer provided with a rotating drum with therein a regenerable drying agent, which drying agent, as a consequence of the rotation of the drum, is alternately brought through two zones of the dryer, whereby in one zone, in particular, a drying zone, said drying agent is used for drying a compressed gas, and in the other zone, more specifically, a regeneration zone, said drying agent is regenerated by bringing this drying agent into contact with a hot gas.
As a result of the rotation of the drum, regenerated drying agent will end up in the drying zone. In order to improve the performances of the dryer, it is suitable and common to provide a third zone, indicated as cooling zone, in the drum, which cooling zone allows to cool the drying agent such that said drying agent can adsorb substantially more moisture.
When such a dryer is used for drying a compressed gas coming from a compressor, a portion of said compressed gas is cooled to be guided subsequently through the drying zone of the dryer, whereby the drying agent in this drying zone extracts moisture from said gas, which consequently results in a dry gas with a low pressure dew point.
The remaining fraction of the compressed gas coming from the compressor and still being hot due to the compression, is guided through the regeneration zone of the dryer, whereby said hot gas desorbs the moisture present in the drying agent, whereby the drying agent is regenerated to allow subsequently, in a new cycle, to be used again in the drying zone to dry the compressed gas.
A disadvantage is that the compressed gas used for regeneration has a relatively high humidity, as a result of which the drying efficiency is not optimal.
The above has the unfavourable result that, when the drying agent is subsequently brought into the drying zone, this drying agent can only absorb a rather limited amount of moisture from the gas being guided through said drying zone.
The heat of the compressed gas is used to regenerate the drying agent in the regeneration zone, whereby it should be noted that, as the temperature of the compressed gas rises, the drying process improves and the efficiency of the installation increases accordingly.
The temperature of the compressed gas used for regeneration, can be raised by installing a heating element or the like, before guiding this gas through the regeneration zone.
A disadvantage thereof is that the heating of the gas flow, used for regeneration, is quite expensive in view of the continuously increasing energy prices.
The invention aims to overcome one or more of said and/or other disadvantages.